It is a common practice to reinforce polyvinyl chloride with particles of elastomers such as polybutadiene and the polyacrylates. The addition of elastomer improves impact strength, i.e., the ability to withstand a rapidly applied shock. While the addition of elastomer improves impact strength, other physical properties such as tensile strength, clarity, heat distortion temperature, hardness and aging stability are, however, adversely affected by the elastomer.
A procedure which is often used to reinforce rigid, brittle polymers involves preparing the plastics in the presence of elastomers. The products resulting from such polymerization procedures, which are referred to as interpolymers or graft copolymers, normally have elastomer contents of about 20-60%. These high elastomer content materials are employed as so-called "impact modifiers" by being blended with brittle plastics in order to enhance their impact strength. The elastomer content of these blends is generally about 5-20%. for example, U.S. Pat. No. 3,632,679 teaches improving impact resistance of PVC by incorporation therein of composite macro-granules comprising rubber C.sub.2 -C.sub.4 alkyl acrylate particles in a PVC matrix.